Lowering the GT is popular modification. Aside of making car look cool, it greatly improves handling. Unfortunately, lowering the car also causes increase of bump-steer effect. Bump-steer is the term for the tendency of the wheel of a car to steer itself as it moves through the suspension stroke (Wikipedia). This is more of a problem on a street car comparing to racing car as the suspension moves up and down more.
The reason for bump-steer at lowered car is changed position of steering tie rods. Optimally tie rods should be parallel to the lower control arms. On a lowered car tie rods point upward which disturbs optimal suspension parallelogram. To put it in simple words, the car gets twitchy on bumpy roads. My GT is lowered 2 (50 mm) by combined use of intermediate spring and longer lower ball joints and I was always joking how it keeps you busy when driving.
Making it one of my winter projects, I decided to correct bump-steer by lowering position of tie rod ends. This is done by installing tie rods under the steering arms. Relatively easy project, with the only difficulty being now wrong orientation of the tapered hole for tie-rod end. I have fixed that by enlarging existing hole and installing steel bushing with inverted tapered hole for tie-rod end. Bushings were made by my buddy Earl in his machine shop. In order to prevent bushing to be pulled out of the arm, the bottom end is flared, similar to the head of countersink bolt. Bushing is pressed in the steering arm for a very tight fit.
Pictures show difference in the position of tie rods before and after modification. Not perfectly parallel position but much smaller angle of the tie rod. Dry weather the other day allowed me to make short run after re-adjusting wheels toe-in. The ride was smooth and the car was noticeably less twitchy. I wish I have done this modification earlier.
I should add that if the car is lowered just 1 (25 mm), there will likely be no need for such modification. 2 (50 mm) lowered car will much benefit if the tie rod position is changed as described. Personally, I found 2 lowering spring way too hard for street use. Intermediate spring plus longer lower ball joint will lower the car 2 but will still keep the ride reasonably comfortable.